How to provide a Session/Host object for use in both a windows and web application?

Question

I have a web application that makes heavy use of the Session state to store information about the current user, their personal settings, record their session history and so on.

I have found myself retrieving this session information in my business layer, like so:

((UserSession)HttpContext.Current.Session["UserSession"]).User.Info

This poses a problem - at some point in the future my application will have a Windows client which obviously cannot reference the web Session state. So I need a host or customized session class that I can reference in my business layer that is agnostic of whether the application is running on the web or desktop. Something like:

IHost.User.Info

Behind the scenes, the web implementation will obviously utilize the Session state to store information, but I need to hide this away from my business layer. Has anyone solved this problem or got any practival advice on how best to approach this?

Help appreciated.

Answer 1

Assuming that the business layer is a separate DLL, I would never add a reference to System.Web and in consequence I would never use the Session object directly. This would lead to a different design of the business layer and of the exposed interfaces to a client (either web or winforms).

That said, as a quick workaround I would suggest to write a wrapper class in your business layer that hides the Session object from your code. Your calls from code will be something like this:

((UserSession) DualContext.Current["UserSession"]).User.Info

and the wrapper implementation will be something like this (not completed and tested):

public class DualContext 
{
   private Dictionary<string, object> winFormsSession = new Dictionary<string, object>();
   private static readonly DualContext instance = new DualContext();

   public static DualContext Current
   {
      get {  return instance; }
   }

   public object this[string key]
   {
      get 
      {
         if (HttpContext.Current != null)
            return HttpContext.Current.Session[key];
         else
            return winFormsSession[key];
      }
      set 
      {
         if (HttpContext.Current != null)
            HttpContext.Current.Session[key] = value;
         else
            winFormsSession[key] = value;
      }
   }
}